I. Field of the Invention
This invention relates to a railway fastening system for holding a rail onto wood or concrete ties, or other supporting structure, while providing a simple and reliable means to allow lateral adjustment of the rail as may be required to maintain gage adjustment, i.e., to compensate for worn rails, and at the same time provide a system having easily replaceable parts so that the system will not be damaged in the event of a derailment or other unexpected event.
II. Description of the Prior Art
The railroads have long used conventional tie plates to fasten rails to wooden ties to distribute the load produced by the wheels of the rolling stock of the railroad, such as railroad cars and locomotives to the ties, which in turn spread the load to the ballast and the ground. The conventional tie plate also is a means of maintenance of the spacing between the rails which is accomplished by the shoulders of the tie plates that control the lateral position of the rail on the tie.
Originally, it was thought that once the tie plate was fastened to the tie, and the rails were fastened to the tie plate, that the lateral position of the rail was fixed and would need no changing. However, as greater and greater loads are placed onto the rails, rail wear has become increasingly evident, especially on the inside, or gage faces, of the rail.
The inside faces of the rail can be worn on level tracks simply by the side-to-side movement of the rail cars, and on curves the situation can be aggravated if the speed of the train does not balance the loads on the curves. At the "curve balanced" speed, both rail faces would carry an equal load, but at an overspeed condition, the high rail takes more gage face wear because the flange rubs against the rail gage face with artificially increased forces. This situation will be reversed at speeds below the balance speed because the low rail will carry more of the force, thus squashing the rail head.
With these conditions becoming aggravated by longer and heavier rail cars, research has been under way as to how to adjust the gage of the rails. It was thought that this could not be done without completely removing the sections of the rail and reversing them, taking a pair of rails off and transposing the same or taking the rails off to a salvage point and welding them into strings for cascading by placing them on a secondary line, etc. However, these approaches are all labor intensive, and thus, very expensive and unsatisfactory. Furthermore, on the new concrete ties with welded rails which can approach a quarter mile long, the process becomes even more difficult, as only transposing an excessively long rail, or moving it to a secondary track, is practical, both of which can be done only at great expense.
In order to provide for lateral adjustment without having to transpose or reverse the rails, it was thought that moving the conventional tie plate over, at least on wood ties, would solve the problem. However, it was found that the amount of adjustment that was needed was very small, such as in quarter inch increments, and that the tie plate could not be moved this small a distance without re-spiking. Also, while the tie plate usually provides for two spike patterns, so that the tie plate can be moved, it was found that the life of the ties was lessened because of the exposure to the elements of the holes which were no longer being used, and this "spike killing" of the tie became very expensive due to reduced life of the tie.
It was thought that the problem of rail gage adjustment, at least for continuous rails on concrete ties, was solved with the invention patented in the U.S. Pat. No. 4,405,081, dated Sep. 20, 1983, to Carl E. Tack, now owned by the assignee of the present application, and also comprising the closest piece of prior art of which I am aware. While the system disclosed in the Tack patent works perfectly as long as there is no damage to the concrete ties such as by derailments, etc., it was found in operation that because the shoulders are one piece and cast into the concrete ties that, if there is any derailment, or near derailment, the shoulders become damaged and unusable, causing the need for replacement of the concrete tie, which is very expensive. Thus, this solution, while previously thought completely adequate, was found to be imperfect, and thus the longstanding problem in the art of how to provide for lateral adjustment of rails on wood and concrete ties still remained.